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Biomedical subjects

P Leger

Publications and source records attributed to P Leger.

At least 19 recordsLinked to original sources
PubMed2006

[What's new in mechanical circulatory assistance: from clinical indications to material].

Over the years, mechanical circulatoryassistance has progressively improved with the evolution of the clinical indications and the introduction of new devices. The management of situations of extreme emergency, cardiac arrest, acute myocardial infarction with cardiogenic shock, drug overdose, acute myocarditis, postoperative cardiac failure and post-transplantation right ventricular failure, may be undertaken with relatively simple systems such as the ECMO, in the catheter laboratory or at the bedside in the intensive care unit. These systems enable stabilisation of the circulatory problems in order to pass a difficult situation and then withdraw the assistance when myocardial function has been restored. When this is not possible and there is no contra-indication to cardiac transplantation, patients may benefit from more complex assistance devices as a bridge to transplantation. Many continuous flow pumps have been introduced recently. These small mono, left ventricular, assist devices provide improved patient comfort and suggest wider indications of long duration assist devices.

Heart Failure↗
PubMed2002

Infrastructure, funding and follow-up in a programme of noninvasive ventilation.

Originating from centres charged with the care of patients with chronic respiratory insufficiency, noninvasive ventilation (NIV) has been used increasingly in chronic and acute respiratory failure during the last decade. Despite a considerable number of series and randomised studies advocating access to NIV for units that treat acute or chronic ventilatory failure, the number of units and the proportion of total ventilatory support remains poor. This is due to lack of education, as many units treat only a few patients per year. Indication, technique, education, monitoring and home care require special experience and a special environment and there is a wide range throughout Europe. With respect to home care in particular, there are many organisations, which range from totally private to hospital based or run for profit. A concerted action, funded by the European Union, will soon provide valuable information about the practice of home ventilation in Europe based on a European survey.

European Union↗
PubMed1999

Preventing, minimizing, and managing postoperative bleeding.

BACKGROUND: Most bleeding in cardiovascular surgery is biological, not surgical, the result of disseminated intravascular coagulation in its latter phases. Disseminated intravascular coagulation bleeding affects all levels of the coagulation systems, requiring stabilization of the platelet system, balancing the procoagulant system and its regulation, and stopping the fibrinolytic system's activation. METHODS: The article discusses the multisystem protocol put into place at the Cardiovascular Surgery Department of La Pitié Hospital in Paris to diagnose and treat DIC bleeding so as to slow down causes of its occurrence and prevent further deterioration of the hemostatic systems. RESULTS: All biological bleeding was controlled, permitting detection of other causes of bleeding and allowing rational use of blood products. No thromboembolic accident occurred. There was an absence of iatrogenic bleeding. The protocol also detects disseminated intravascular coagulation in patients who did not bleed to take early and frequently lifesaving measures. CONCLUSIONS: This demonstrates the need to treat bleeding through a multisystem approach, monitoring its evolution by means of biological tests to be able to provide appropriate treatment.

Blood Coagulation Tests↗
PubMed1999

Chronotropic competence in endurance trained heart transplant recipients: heart rate is not a limiting factor for exercise capacity.

OBJECTIVES: The purpose of this study was to show that the chronotropic potential of the well trained heart transplant recipient (HTR) does not limit exercise capacity. BACKGROUND: Chronotropic incompetence is considered to be the main limiting factor of the functional capacity of heart transplant recipients. However, no systematic study had been published on patients who had spontaneously undergone heavy endurance training for several years. METHODS: Heart rate (HR) and respiratory gas exchanges (VO2, VCO2, VE) were measured in 14 trained HTRs (T-HTRs) during exercise tests on a bicycle, on a treadmill and by Holter electrocardiography during a race. RESULTS: Peak values observed in T-HTRs during the treadmill test were higher than those reached during the bicycle test (VO2peak: 39.8+/-6.9 vs. 32.5+/-7.8 ml x kg(-1) x min(-1), p < 0.001; HRpeak: 169+/-14 vs. 159+/-16 bpm, p < 0.01). During treadmill exercise VO2peak and HRpeak values observed were very close to the mean predicted VO2pmax and HRpmax. The maximum heart rate during the race (HRrace) was greater than HRpeak values during the treadmill test (179+/-14 vs 169+/-14 bpm, p < 0.01) and slightly above the mean predicted values (HRrace/HRpmax X 100 = 101+/-10%). The treadmill exercise test yields more reliable data than does the bicycle test. CONCLUSIONS: Extensive endurance training enables heart transplant recipients to reach physical fitness levels similar to those of normal sedentary subjects; heart rate does not limit their exercise capacity.

Adult↗
PubMed1999

The art of interface. Tools for administering noninvasive ventilation.

BACKGROUND: Since the choice of interface plays a large role in the effectiveness of noninvasive ventilation, there is a need for information about what is available, how to make a selection, what to do when a problem occurs, and how to provide proper care and monitoring. MATERIAL AND METHODS: Here we will present some of the different types of interfaces available, different problems presented by each, and guidelines for making choices among them.

Humans↗
PubMed1999

Comparative of blood flow to the ankle-brachial index after iliac angioplasty.

BACKGROUND: Interest of blood flow and ankle brachial pressure index (ABPI) to evaluate result of iliac angioplasty. METHODS: ABPI and blood flow rates were measured before and after angioplasty in 22 lower extremities of 16 patients with iliac stenosis. Blood flow rates were determined by means of a nuclear magnetic resonance (NMR) flow meter. RESULTS: The day after angioplasty, flow and pressure were increasing significantly, whereas a month later, only blood flow was increasing significantly. In a group of patients with near-normal ABPI before angioplasty (ABPI > or = 0.8), there was, on the day following the angioplasty, a significant increase in ABPI and pulsatile blood flow rates; flow rates increased considerably a month after the operation whereas ABPI stay stable. In a group of patients with clearly abnormal ABPI before angioplasty (ABPI <0.80), there was a significant increase in ABPI and blood flow rates the day after angioplasty and again a month later. CONCLUSIONS: Flow therefore seems to vary independently of pressure. The possible use of flow measurement to detect restenoses is yet to be studied.

Adult↗
PubMed1999

Higher-order spectral analysis in laser-Doppler flowmetry signal processing.

This paper presents an application of higher order statistics and spectra to the problem of laser-Doppler Flowmetry (LDF) for microcirculation monitoring. The proposed signal processing technique computes the bispectra of LDF signals after appropriate pre-processing and extracts features which can be used for classification of the signals to a normal or patient category. Bispectra are defined in terms of the third-order moments or cumulants of signals and are shown to contain valuable information for the above classification of LDF signals. Experimental studies, including (a) a set of 17 normal subjects and 69 patients with Raynaud's phenomenon and (b) 50 LDF-signals separated to four groups from patients that have different pathologic characteristics, are described and results are presented which illustrate the performance of the proposed approach when applied to the LDF signals.

Adult↗
PubMed1999

Time-variant spectral analysis of LDF signals on the basis of multivariate autoregressive modelling.

Time-variant AR-modelling was used to analyse the non-stationary properties of LDF signals during provocation tests. The procedure for the estimation of time-varying AR parameters based on Kalman filtering is presented. The estimates can be used to calculate instantaneous measures, such as peak frequency, spectral band power and coherence. The resulting course of instantaneous peak frequency of a sinusoidal signal with frequency jump was compared to similar parameters derived from short-time FFT and Hilbert transformation. Univariate time-variant spectral analysis was used to investigate LDF measurements in patients with Raynaud's phenomena. The experimental protocol was splitted into phases of different room temperature. The results demonstrate time-dependent variations of spectral components (amplitude and frequency). By means of time-variant coherence analysis of LDF and diameter measurements of vessels in a hamster skin fold the existence of a main rhythm around 0.1 Hz in the LDF signals which is related to vasomotion is shown.

Algorithms↗
PubMed1999

Different flowmotion patterns in healthy controls and patients with Raynaud's phenomenon.

Flowmotion was characterized in healthy controls and 61 Raynaud's phenomenon (RP) patients by spectral analysis of laser-Doppler perfusion monitoring (LDPM) tracings. Healthy subjects flowmotion patterns revealed a main frequency of 3 cycles per min (cpm) with another low frequency and heart rate synchronous components. A first group of RP patients presented a low frequency and heart rate frequency component but no significant difference in blood flow. The second group presented the predominating heart rate related frequency with low microvascular perfusion. The third group presented a flowmotion pattern with overlapping of heart rate and low frequency components. Patients with primary and secondary RP show specific changes in flowmotion, probably related to increased sympathetic nervous activity or vessel wall alterations causing disappearance of arteriolar tone and impairment of microvascular perfusion. The group of patients with overlapping frequency components presents an intermediate flowmotion pattern indicating a different grade of alterations in microvasculature.

Adolescent↗
PubMed1999

Spectral analysis of laser-Doppler perfusion signal measured during thermal test.

The method of spectral analysis of laser-Doppler perfusion signal measured during thermal test is proposed. During three 20 min phases with 40, 5, and 40 degrees C of thermal test laser-Doppler perfusion signal was recorded. For each signal phase frequency spectra were calculated using the FFT method. Quantitative parameter Spectral Factor for results evaluation was proposed. In total 94 patients were measured: 69 with Raynaud's phenomenon and 25 normal subjects. Additionally in 18 Raynaud's patients the influence of Nifedipine was studied. Results suggest that proposed parameter is able to differentiate between Raynaud's patients and normal subjects and that is useful for evaluation of Nifedipine effectiveness. However, further studies are needed to improve the method to differentiate between primary and secondary Raynaud's patients.

Adult↗
PubMed1999

Dynamic characteristics of laser-Doppler flux in normal individuals and patients with Raynaud's phenomenon before and after treatment with nifedipine under different thermal conditions.

The study was aimed at choosing an appropriate characteristic of laser-Doppler flux (LDF) data for (1) distinguishing patients with Raynaud's disease from normal controls and (2) evaluating the effect of nifedipine under different thermal conditions. We checked the reliability of three characteristics of nonlinear dynamics as statistical dimension Ds, correlation dimension D2 and power-law index PLI. Their values depended heavily on the thermal condition. The most reliable characteristics that enabled us to distinguish the patients from normal controls and the effect of nifedipine under definite thermal condition proved to be Ds and PLI. The latter is simple for computation and is thus recommendable for clinical practice. Ds and PLI were higher in patients with Raynaud's compared to normal controls and diminished during the transitions from low to high temperature. However, the characteristics used were unable to distinguish significantly Raynaud's I from Raynaud's II patients.

Algorithms↗